Engineered to Fail · Part 2 of 6

Known Human Limits in Capability Programmes: Why the Action Comes From Below

Tolerance failures in Defence are rarely discovered. They are recorded, published, given a delivery date, and then deferred. What changes the outcome is usually pressure from the people carrying the risk.

Dr Anthony Walker, PhD in thermal and occupational physiology. Founder and Managing Director, Optimised Human Performance.
Published 28 September 2026.

Were the body armour and uniform problems actually unknown?

No. In July 2021 the UK House of Commons Defence Committee reported on women in the Armed Forces. In its survey, 1,259 currently serving women disagreed that their uniform was appropriate for their needs, which the Committee described as "more than three-quarters (77%) of all currently serving female personnel who participated." A further 977 "expressed concerns over their equipment." The Committee recorded that "Failure to design body armour and combat equipment for women was also widely reported as a safety issue", and that "There were also stories of helmets falling over women’s eyes, so they could not see when firing."

Its finding was direct: "Thousands of female Service personnel, already facing the dangers of military duty, are at greater risk of harm due to basic failures in their uniform and equipment, which can have consequences for their combat effectiveness and health."

What happened once the limits were on the record?

The Government’s response in December 2021 committed to a timetable. A female-optimised VIRTUS vest was "to be delivered in Spring/Summer 2022", and "An interim solution of a smaller OSPREY plate will be introduced by the end of 2022". In March 2025 a defence minister told Parliament that the Tactical Ballistic Plate programme, which will replace the existing plates, "is expected to deliver from 2027." Asked again in May 2025, the answer was that "Defence is an active participant in NATO work to explore options to further optimise body armour for our Service personnel, including for females."

Nothing in that sequence was an unknown. The people wearing the armour reported the problem, a parliamentary committee published it, and a government set dates. The durable fix is still described in the future tense.

Why does the action so often come from the people carrying the risk?

The US Navy’s physiological episodes show the same pattern with a different ending. In February 2018 the chairman of the House Armed Services subcommittee explained how the Navy’s T-45 training fleet came to be grounded: "The decision was made after a significant number of instructor pilots at all three T-45 training locations refused to fly the aircraft due to safety concerns with the oxygen systems." He went on: "It is an incident that we were very concerned about in this committee that would have to go to the level of the pilots themselves intervening and refusing to fly, prior to leadership understanding the need to intervene."

The technical cause proved hard to isolate. A year later, the F/A-18 programme office was still investigating breathing factors including "work of breathing", and Don Salamon, a deputy assistant programme manager for systems engineering, said, "There is likely no single ‘smoking gun’ that will be found as a result of the investigation." That difficulty is exactly why the trigger matters. The institution committed to a sustained investigation after the people exposed to the hazard withdrew their willingness to carry it.

How current are the anthropometric standards behind equipment design?

We wore structural firefighting helmets to every rescue event. They are heavy and bulky, designed to protect against the impact of a falling roof rather than to be worn in the tight confines of a rescue. Lighter helmets existed. The decision to adopt them sat for years, and it moved only after a change of guard at the highest level, when people who had spent their careers on the front line finally reached a position where they could act against the "always done it that way" cartel.

How often do we see teams "pinking and shrinking" equipment rather than taking the time and effort to ensure everybody has access to equipment that is right for them? How up to date are the anthropometric standards we measure capability designs against, and were they drawn from the right population in the first place? Those two questions decide whether a design brief reflects the people who will use the equipment or a population that has already changed.

Where would this argument be wrong?

Tolerance failures in Defence are rarely unknown. They are known and deferred, and the action tends to come from below: a survey that forces a committee’s hand, or instructors who refuse to fly.

The evidence that would weaken this claim is a case where a tolerance limit was acted on before the people carrying it had to force the issue. If you have one, I want it.

Dr Anthony Walker holds a PhD in thermal and occupational physiology and served fifteen years in operational firefighting, including station officer command. He is Founder and Managing Director of Optimised Human Performance, a specialist consultancy in human systems integration and work system design for Defence, aviation, emergency services and resources clients.